High viscosity index synthetic polymer lubricants



United States Patent This invention relates to the production of synthetic lubricants from synthetic polymer fluids. More particularly, this invention is concerned with a process wherein polypropylene oils are subjected to cracking in the presence of platinum-containing catalysts to produce synthetic oils having improved lubricating properties and high quality jet combustion fuels.

As is well known to those skilled in the art, the synthetic oils produced by the polymerization of olefinic hydrocarbons such as, for example, propylene, are lacking in certain characteristics and properties desirable in lubricating oils. Thus, the synthetic polymer fluids heretofore available have characteristically exhibited poor temperatureviscosity relationships. All such previously known synthetic polymer oils have had a viscosity index (V.I.) within the range of from about 30 to about 60. No high V.I. oils, i.e., oils having aV.I. of the order of at least about 80, have hitherto been prepared by the polymerization of hydrocarbons. Accordingly, the production of olefinic hydrocarbons has been and remains a highly desirable objective of the lubricant industry.

It has now been found, in accordance with the present v ence of hydrogen, a halogen promoter, and a catalyst comprising a catalyst member having hydrogenation activity and a catalyst member having a relatively low level of cracking activity, specifically a platinum or palladium series metal supported upon alumina. It is a further dis: covery of this invention that the light distillate fraction of the product of such cracking 'is an excellent fuel for jet A further object is to provide a catalytic cracking process wherein the cracking etfected is a hydrocracking of a highly selective nature. -A more specific object is to provide a process for the hydrocracking of polypropylene oils in the presence of a halogen promoter and of a catalyst comprising a member having hydrogenation activity and a member having cracking activity of a relatively low order. Another specific object is to provide a process for producing fuelsfor jet combustion engines. Other objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description.

In general, the present invention provides a process for the production of synthetic oils of improved lubricating properties and jet combustion fuels from polypropylene oils which comprises contacting a polypropylene oil in the presence of hydrogen charged at a rate varying between about 1,000 and about 5,000 standard cubic feet (s.c.f.) per barrel of polypropylene oil per hour, with a catalyst comprising from about 0.05 percent to about 20 percent, by weight of the catalyst, of a metal selected from the group of metals having atomic numbers of 44 to 46, inclusive, and 76 to 78, inclusive, and alumina, under hy- 3,084,205 Patented Apr. 2, 1963 drogen pressure of from about 350 pounds per square inch gauge to about 700 pounds per square inch gauge, at a liquid hourly space velocity (liquid volume charge/ volume catalyst/hour) of between about 1 and 4, and at a temperature varying between about 500 F. and about 650 F.

As is well known in the art, the term cracking designates an operation wherein mixtures of hydrocarbon molecules of relatively high molecular weight are converted into mixtures of hydrocarbon molecules of lower molecular weight. True hydrocracking, as the term is conventionally employed in the petroleum industry, refers to a cracking process which is carried out under hydrogen pressure and in the presence of a catalyst having both cracking activity and hydrogenation activity. The uniform tendency of such an operation is to break the basic molecular skeleton of the hydrocarbon molecule undergoing the operation. The term, selective hydrogenation, as employed throughout the specification and claims, is intended to mean a cracking process carried out under hydrogen pressure in the presence of a catalyst comprising a metal having hydrogenation activity supported on alumina and of a promoter comprising a suitable source of halogen. It has been found that such an operation does not act to break the basic molecular structure of the hydrocarbon molecule treated but rather effects a shearing action resulting in the removal of the branched chains appended to the basic hydrocarbon moiety. The cracking activity of the component of the catalyst having cracking activity is expressed in terms of the percentage, by volume, of a standard hydrocarbon charge which is cracked, under specific operating conditions, in the Cat. A test. This test is described in Nat. Pet. News 36, pages R-357 (August 2, 1944). The unit for rating the cracking activity of a material is called the Activity Index (A1.)

The synthetic polymer fluid which is treated in accordance with the process of the present invention is any oily liquid product resulting from the polymerization of pro? pylene. The polypropylene oils can be prepared in accordance with procedures which are well known to those skilled in the art. Illustratively, a polypropylene oil 'suitable for use in the process of the present invention can be perpared in accordance with the procedure disclosed in the US. Patents Nos. 2,315,080 and 2,318,719. The

' polypropylene oils contemplated herein have molecular weights in the order of about 600-900 and have SAE viscosity numbers of 140, i.e., between about *25' anus F. and 42.9 cs. at 210 F., and of 250, i.e., above 42.9 cs. at 210 F. These oils are' characterized by relatively poor viscosity-temperature relationships and have viscosity indices of about 60 and lower. 7 W V i As heretofore disclosed, the catalysts employed. in the process of the present inventionare comprised of one component having hydrogenation activity and a second component having a relativelylow order of crackingactivity. Thus, the catalyst will comprise at least onemetalofthe platinum and palladium series deposited upon an alumina carreir. The amount of metal deposited on the carrier can vary from about 0.05 percent by weight and about 20 percent byweight of the final catalyst, and, preferably, will be from about 0.1 percent to about 5.0 percent. The metal deposited can be a single member of the series or it can be a mixture or alloy of such members. These cat alysts can be prepared by any of the methods well known to those skilled in the art. For example, one suitable method involves impregnating alumina with a platinum compound, such as chloroplatinic acid, calcining the impregnated carrier and reducing and activating the platinum in the presence of hydrogen.

The selective hydrocracking process of the present invention is carried out at relatively low temperatures. While the range of operable temperatures will vary to some degree depending on the precise nature of the catalyst, it has been determined that satisfactory production of synthetic oils having the desired viscosity index is effected at temperatures ranging between about 525 F. and 650 F. Preferably, the selective hydrocracking process is carried out at a temperature within the range of 600-650 F. It has further been determined that it is not feasible to employ temperatures substantially in excess of about 650 F.

The hydrogen pressure employed in carrying out the process of the present invention varies between about 350 pounds per square inch gauge and about 700 pounds per square inch gauge, preferably, however, between about 350 and 500 pounds per square inch gauge. The liquid hourly space velocity, i.e., the liquid volume of synthetic polymer fluid per hour per volume of catalyst, varies between about 1 and about 4, preferably between about 1.5 and about 2.5. In general, the hydrogen flow rate will be between about 1,000 and about 5,000 standard cubic feet (s.c.f.) per barrel of polypropylene oil per hour, and preferably between about 1900 and about 3200 s.c.f. per barrel of polypropylene per hour. 7

In the operation of the selected hydrocracking process of this invention, the variables of temperature, LHSV, and amount of halogen promoter are interdependent, as those skilled in the art will readily appreciate. Thus, when operating at higher temperatures, higher space velocity and a lower amount of halogen promoter are used. Low space velocity or greater amount of halogen promoter, or both, can be used at temperatures in the lower end of the specified range. Pressure is less of a factor than the aforementioned variable.

The halogen promoter can be any halogen source. Hence, the promoter can comprise any of the halogens, i.e., chlorine, bromine, fluorine, and iodine, as such, or in the form of organic or inorganic compounds thereof. Thus, and for purposes of illustration only, the promoter can be introduced into the reaction unit in the form of F., corresponding to SAE viscosity numbers of between 15 and 30. They have viscosity indices of about 75 and higher. The preferred lubricant properties have viscosity indices greater than about 100 and up to about 148, although the latter V.I. was attained at the expense of a relatively low yield. The molecular weights of the polymer oil products range from about 300 to about 550.

In order that the invention may be more fully understood, the following specific examples are provided. It is to be understood, however, that such examples are for purposes of illustration only and are not to be construed as lirnitative of the present invention, the scope of which is commensurate with the claims appended hereto.

EXAMPLES 1 THROUGH 17 A series of hydrocracking runs were made using three different polypropylene oils of various molecular weights, as set forth in Table I. In order to facilitate pumping, the polypropylene feed was diluted 1:1 (volume) with nhexane. All these polypropylene oils were prepared by conventional polymerization of propylene in the presence of AlCl Each run was carried out using a different set of operating conditions within the aforedescribed broad ranges. The amount of halogen promoter, charged as chloroform, was varied.

All runs were carried out in a continuous flow stainless steel reactor having a feed preheater zone and containing a 100 ml. fixed-bed catalyst zone. The catalyst used comprised 06 weight percent platinum supported on an alumina base. At the end of each run, the hydrocracked efiluent was topped to 150 C. to remove hexane solvent. Then, the product was subjected to distillation at a pot temperature of about 260 F. under 1 mm. mercury pressure (about 600 F. at atmospheric pressure), to remove light distillate product. .This product boils in the kerosene boiling range. The remaining, undistilled product is the hydrocracked polypropylene oil of this invention.

Pertinent process, charge stock, and product data are C1 or it may be added as a suitable organic chloride, such set forth in Table I.

Table I Residual Oil Product LHSV Pres- H: flow Example No. Charge Stock Rate 1 poly- Percent Temp., sure, rate, s.c.f./

ctr/hr. propyl- 01 F. p.s.i.g. bb./hr. Per- K.V.@ K.V.@ Avg. one cent 100 I 210 F. V.I. M01.

Yld. Wt.

0. 59 910. 0 33. 8 300 1. 5 0.3 525 700 3, 160 32. 2 5. 4 0. 1 1, 513. 0 45. 2 400 2 0. 3 500 700 2, 300 96 l, 208 40. 4 400 2 0.3 500 350 2, 300 97 1, 698 48. I 400 2 0.3 600 350 2, 300 85 325 19. 3 400 2 0. 5 600 350 2, 300 51 19. 7 4. 0 400 Z 0. 5 600 500 2, 300 53 17. 0 3. 7 400 2 0. 1 1, 048. 0 35. 7 400 2 0. 1 600 350 2, 300 88 414.0 21. 6 400 2 0. 3 600 350 2, 300 70 139. 0 11. 6 400 2 0. 5 600 350 2, 300 59 80.0 8. 9 400 Z 0. 5 600 500 2, 300 78 158. 0 12. 8 400 2 0. 5 650 350 2, 300 14 32. 0 5. 3 800 4 0. 5 650 350 I, 200 52 26.0 4. 6 800 4 0. 3 650 600 1, 200 48 6. 4 200 1 0. 5 600 350 4, 600 33 104. 0 10. 4 200 1 0. 3 650 350 4. 600 24 24. 0 4. 4 200 1 0. 75 650 350 4, 600 2 800 4 0. 5 650 350 1, 200 19 18. 0 4. 1

It will be noted that the data set forth in Table I illustrate various combinations of conditions that produce cracked polypropylene oils within the scope of this invention. The data also show the efiect of too low a halogen content and too low a temperature (Examples 2 and 3). The effect of too low a halogen content alone, at the conditions used, is shown in Examples 3 and 7. In Example 16, the elfect on yield is shown, when the LHSV is too low at a high halogen content and high temperature. The relatively little effect of pressure is evident from a comparison of Examples 5 and 6. The run of ranging between about 3.5 cs. and about 12 cs. 210 Example 17 illustrates that very high viscosity indices can be achieved by the process of this invention, albeit at the expense of yield.

EXAMPLE 18 It was set forth in Examples 1-17 that the light distillate product of the process of this invention boils in the kerosene range. Thus, this distillate product is useful as a jet fuel. Typical properties of this fuel are:

ASTM Test D1740-60T.

From Example 18, it will be apparent that the process of this invention provides a useful jet fuel as well as a high V.I. oil. As shown in the examples, this fuel was obtained by distilling to about 260 F. at one mm. mercury pressure. This is equivalent to about 600 F. at atmospheric pressure. As will be apparent to those skilled in the art, light distillate product can be removed by atmospheric distillation up to 600 F., or by distillation up to any temperature at reduced pressure that is equivalent to 600 F. at atmospheric. In the appended claims the use of the term boiling up to about 600 F. at atmospheric pressure, or similar terminology, is inclusive of the equivalent temperature at reduced pressure.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A process for the production of synthetic oils of improved lubricating properties and jet combustion fuel from polypropylene oil which comprises contacting said polypropylene oil in the presence of hydrogen charged at a rate varying between about 1,000 and about 5,000 standard cubic feet per barrel of polypropylene oil per hour, with a catalyst comprising from about 0.05 percent to about 20 percent, by weight of the catalyst, of a metal selected from the group of metals having atomic numbers of 44 to 46, inclusive, and 76 to 78, inclusive, and alumina, under hydrogen pressure of from about 350 pounds per square inch gauge to about 700 pounds per square inch gauge, at a liquid hourly space velocity (liquid volume charge/ volume catalyst/ hour) of between about 1 and 4, and at a temperature varying between about 525 F. and about 650 F.; in the presence of 6 between about 0.2 percent and about 0.8 percent, by weight of said polypropylene oil, of a halogen.

2. A process for the production of synthetic oils of improved lubricating properties and jet combustion fuel from polypropylene oil which comprises contacting said polypropylene oil in the presence of hydrogen charged at a rate varying between about 1,000 and about 5,000 standard cubic feet per barrel of polypropylene oil per hour, with a catalyst comprising from about 0.1 percent to about 5 percent, by weight of the catalyst, of platinum and alumina, under hydrogen pressure of from about 350 pounds per square inch gauge to about 700 pounds per sqare inch gauge, at a liquid hourly space velocity (liquid volume charge/volume catalyst/hour) of between about 1 and 4, and at a temperature varying between about 525 F. and about 650 F.; in the presence of between about 0.2 percent and about 0.8 percent, by weight of said polypropylene oil, of a halogen.

3. A process for the production of synthetic oils of improved lubricating properties and jet combustion fuel from polypropylene oil which comprises contacting said polypropylene oil in the presence of hydrogen charged at a rate varying between about 1,900 and about 3,200 standard cubic feet per barrel of polypropylene oil per hour, with a catalyst comprising from about 0.1 percent to about 5 percent, by weight of the catalyst, of platinum and alumina, under hydrogen pressure of from about 350 pounds per square inch gauge to about 500 pounds per square inch gauge, at a liquid hourly space velocity (liquid volume charge/ volume catalyst/hour) of between about 1.5 and 2.5, and at a temperature varying between about 600 F. and about 650 F.; in the presence of between about 0.2 percent and about 0.8 percent, by weight of said polypropylene oil, of a halogen.

4. A process for the production of synthetic oils of improved lubricating properties and jet combustion fuel from polypropylene oil which comprises contacting said polypropylene oil in the presence of hydrogen charged at a rate varying between about 1,900 and about 3,200 standard cubic feet per barrel of polypropylene oil per hour, with a catalyst comprising from about 0.1 percent to about 5 percent, by weight of the catalyst, of platinum and alumina, under hydrogen pressure of from about 350 pounds per square inch gauge to about 500 pounds per square inch gauge, at a liquid hourly space velocity (liquid volume charge/volume catalyst/hour) of between about 1.5 and 2.5, and at a temperature varying between about 600 F. and about 650 F.; in the presence of between about 0.3 percent and about 0.5 percent, by weight of said polypropylene oil, of a halogen charged as chloroform.

2,918,507 Kennedy et a1 Dec. 22, 1959 Gurd et al. Oct. 3, 1961 

1. A PROCESS FOR THE PRODUCTION OF SYNTHETIC OILS OF IMPROVED LUBRICATING PROPERTIES AND JET COMBUSTION FUEL FROM POLYPROPYLENE OIL WHICH COMPRISES CONTACTING SAID POLYPROPYLENE OIL IN THE PRESENCE OF HYDROGEN CHARGED AT A RATE VARYING BETWEEN ABOUT 1,000 AND ABOUT 5,000 STANDARD CUBIC FEET PER BARREL OF POLYPROPYLENE OIL PER HOUR, WITH A CATALYST COMPRISING FROM ABOUT 0.05 PERCENT TO ABOUT 20 PERCENT, BY WEIGHT OF THE CATALYST, OF A METAL SELECTED FROM THE GROUP OF METALS HAVING ATOMIC NUMBERS OF 44 TO 46, INCLUSIVE, AND 76 TO 78, INCLUSIVE, AND ALUMINA, UNDER HYDROGEN PRESSURE OF FROM ABOUT 350 POUNDS PER SQUARE INCH GAUGE TO ABOUT 700 POUNDS PER SQUARE INCH GUAGE, AT A LIQUID HOURLY SPACE VELOCITY (LIQUID VOLUME CHARGE/VOLUME CATALYST/HOUR) OF BETWEEN ABOUT 1 AND 4, AND AT A TEMPERATURE VARYING BETWEEN ABOUT 525* F. AND ABOUT 650* F.; IN THE PRESENCE OF BETWEEN ABOUT 0.2 PERCENT AND ABOUT 0.8 PERCENT, BY WEIGHT OF SAID POLYPROPYLENE OIL, OF A HALOGEN. 